The class of polymers of carbon monoxide and olefin(s) has been known for a number of years. Brubaker, U.S. Pat. No. 2,495,286, produced such polymers of relatively low carbon monoxide content in the presence of free radical initiators, e.g., peroxy compounds. U.K. No. 1,081,304 produced similar polymers of higher carbon monoxide content in the presence of alkylphosphine complexes of palladium salts as catalyst. Nozaki extended the reaction to produce linear alternating polymers in the presence of arylphosphine complexes of palladium moieties and certain inert solvents. See, for example, U.S. Pat. No. 3,694,412.
More recently, the class of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon, now commonly known as polyketones or polyketone polymers, has become of greater interest in part because of the greater availability of the polymers. The more recent general processes for the production of the polyketone polymers are illustrated by a number of published European Patent Applications Nos. including 121,965, 181,014, 213,671 and 257,663. The processes involve the use of a catalyst composition formed from a compound of a Group VIII metal selected from palladium, cobalt or nickel, the anion of a non-hydrohalogenic acid having a pKa below about 6, preferably below 2, and a bidentate ligand or phosphorus, arsenic or antimony.
The resulting polymers are relatively high molecular weight materials having utility as premium thermoplastics in the production of shaped articles such as containers for food and drink by processing methods which are conventional for thermoplastics. The polymers are relatively crystal)ine materials with well defined melting points. However, during processing operations which involve multiple melting/solidification cycles, the polymers do tend to lose crystallinity which may have an adverse effect on certain of the desirable properties of the polymer. It would be of advantage to provide compositions of the linear alternating polymers which are stabilized against undue loss of crystallinity, i.e., have an improved melt stability, upon being subjected to melting and solidification.